The present invention relates to an improved electrified composite metal/concrete floor.
Such floors are well known and comprise a corrugated metal decking over which concrete is poured. Such floors are often electrified in that electrical power and telephone and other communication services are distributed in the cells underlying the raised portions or crests of the decking, with access to the interior of the cells from the upper surface of the floor provided by inserts preset at selected intervals prior to the concrete pour. Access by the services to the interior of the longitudinal cells is generally provided by a lateral trench overlying the metal decking, which trench includes parallel rails covered with a metal plate coplanar with the upper surface of the concrete floor when poured.
In one aspect, the present invention includes a novel metal decking profile, with grooves adjacent the lateral edges of the crests to receive the concrete of the composite floor, stable when stacked during shipment to the job site.
Grooves adjacent the crests of decking to receive concrete are well known. For example, FIG. 4 of the French Patent No. 1,176,824 granted Nov. 28, 1958 to Wendel shows a decking profile in which the radii of the bend at the lateral edge of the crest and the bottom of the groove are equal and in which the centers for the bends are vertically spaced approximately twice such radii. Concrete enters the groove to enhance the metal/concrete interaction, i.e., "composite action", when the concrete is poured. Stacking is stabilized by making the radius bend of the lateral edge of the lower side of the groove slightly larger than such radii to mate with the lateral edge of an underlying decking member. However, the semi-cylindrical radius bends do not provide adequate deformation resistance to downward pressure from the lateral edges of the crests.
Grooves adjacent the lateral edge of metal decking are also shown in the Ting U.S. Pat. No. 4,453,364 dated June 12, 1984. In that patent, the grooves have a horizontal lower side and an upper side joining the radius bend of the lateral edge of the crest at an angle of approximately forty-five degrees. The Ting grooves are constructed such that (a) the lateral edge of the crest is at or inside of the plane of the sidewall and (b) a vertical line passing through the lateral edge of the crest intersects the sidewall structure at a point inside the plane of the sidewall, i.e., intersects a groove in the sidewall rather than the sidewall or any projection therefrom. While bending resistance is enhanced, the amount of concrete which can enter the groove is inadequate when cover plates are used. Moreover, the location of the lateral edge of the crests interiorly of the intersection of the planes of the sidewall and the crests results in instability in stacking.
The decking profiles of the present invention combine the stacking stability and metal/concrete interaction of Wendel with the improved strength of Ting, and further enhance the metal/concrete interaction. In one embodiment, this improvement is obtained by increasing the vertical separation of the centers of the radius bends of the crest and groove so as to join the groove and crest edge at an angle of approximately forty-five degrees. Stacking stability is enhanced by the matching of the radius bends of the side wall and crest. In another embodiment, the decking profile of the present invention further enhances composite action by establishing a projection in the side wall immediately below the groove to thereby extend the horizontal lower wall of the groove. Stability when stacked is enhanced by the abutment of the projection with the side wall at a point on the side wall below the crest.
In other embodiments, the center of the projection is displaced outwardly so as to increase the shoulder on which cover plates may rest.
In another aspect, the decking profile of the present invention has a central valley significantly wider than the side-lap valleys and wider than the crests. Conventional decking sections such as disclosed in the Albrecht, et al. U.S. Pat. No. 3,812,636 dated May 28, 1974, and the aforesaid Ting patent have central and side lap valleys of approximately equal width.
A third embodiment of the decking profile of the present invention provides adequate space for the use of studs in securing the side-lap valleys to the structural beams, while greatly increasing the effective space in the central valley where the services are provided. The structural properties of the sections are enhanced by upwardly projecting cell dividers as explained infra in more detail.
In a fourth embodiment, the cell dividers in the central valley decking profile are elevated to a height adjacent the height of the crests, further enhancing the structural properties of the decking member and permitting the use of lighter gauge metal. Raising the cell dividers also increases the capacity of the central cell.
The elevation of the cell dividers permits attachment of the preset inserts through the cover plate directly to the decking member, thereby providing an electrical ground and avoiding the necessity for a secure metal-to-metal attachment of the cover plate to the decking member along the lateral edges of the cover plate. The elevation of the cell dividers also permits the use of the same cover plate with decks of different depth.
In another aspect, the present invention includes snap-in cover plates for selected valleys of the decking to form longitudinal cells for electrification of the floor. Longitudinal cells for this purpose are well known. They may be formed by welding of the decking to an underlying plate as disclosed in the Penczak U.S. Pat. No. 4,041,238 dated Aug. 9, 1977, the Fork U.S. Pat. Nos. 4,178,469 dated Dec. 11, 1979, or 3,426,802 dated Feb. 11, 1969; or the Littrell U.S. Pat. No. 4,338,484 dated July 6, 1982. They may also be formed by snap-in plates beneath the crests of the decking as disclosed in the Fork U.S. Pat. No. 4,194,332 dated Mar. 25, 1980, and the Albrecht, et al. U.S. Pat. No. 3,812,636 dated May 28, 1974. The decking, however, is structurally weakened by the apertures necessary for access to the cells.
Others have avoided the problem of decking penetration by providing cover plates for a valley to thereby create a longitudinal cell within the valley. Systems of this type are disclosed in the Fork European Patent No. 0003506, the Fork U.S. Pat. No. 3,592,956 dated July 13, 1971, or the Lee, et al. U.S. Pat. No. 2,912,848 dated Nov. 17, 1959.
However, such systems generally provide a smooth upper surface with reduced composite action, do not provide for separation of services within the cell, span the valley without intermediate support, are not resiliently compressible for snap-in and do not have upturned lateral edges for prevention of water seepage during the concrete pour.
Other systems, such as disclosed in the Ting U.S. patent application No. 340,869 filed Jan. 20, 1982 (now abandoned), utilize grooves adjacent the crests for retention of the flat cover plates. While lowering the cover plate provides an upturned edge for prevention of water seepage, the reduced height of the cell is generally unacceptable because of the resultant reduced capacity for all services, and the capacity (i.e., cross-sectional area) determines the number of wires and hence the length that a cell can branch out from the feeder or trench header. The aforementioned Ting application also teaches support of the cover plates intermediate the crests by two interconnected but spaced apart legs which separate the valley into two equal volume cells. However, such cover plates rely on concrete between the legs for strength, and thus further reduce the volume or capacity of the two cells, i.e., the use of parallel legs spaced sufficiently apart for concrete to enter therebetween significantly reduces the capacity of the two cells.
The cover plates of the present invention are stackable for shipment to the job site and are easily installed from above the decking. As contrasted with decking which must span from beam to beam and is thus installed by steel workers, the cover plates may be of shorter length and installed by electricians walking on the deck, thus greatly reducing installation costs.
The cover plates may provide two unequal capacity cells, or three cells of the same or different capacity, in the same valley. In one embodiment, they may be made of sheet metal and provided with one or two double walled legs to provide support intermediate the crests. The legs may be shaped and/or otherwise constructed to enhance lateral resiliency and thus secure a positive snap-lock engagement with the grooves. Metal/concrete interaction is retained and additional space for three services is provided by the selective raising of a portion of the cover plate above the point of connection thereof to the sidewalls, even to the same height as the crests, and by the substantial elimination of concrete between the walls of the legs. The decking profile permits the entry of significant concrete into the grooves with the lateral edges of the cover plate engaged therein, and even with the lateral edges of the preset inserts engaged therein as described infra. In three cell embodiments, the center section may be lowered to facilitate access to the two side cells. This lowering of the center cell provides adequate space for the nearly vertical mounting of electrical receptacles and increases the volume and thus the capacity of the preset inserts to house related accessories.
In still another aspect, the present invention includes a preset insert uniquely cooperating with the cover plates for access to the cells defined by the valley of the decking member and the cover plate. Known preset inserts such as disclosed in the Fork U.S. Pat. No. 3,932,696 dated Jan. 13, 1976 and Penczak U.S. Pat. No. 4,041,238 dated Aug. 9, 1977 span adjacent crests and are designed to provide access to cells beneath the crests. Others, such as Fork U.S. Pat. No. 3,417,191 dated Dec. 12, 1968, fit between the crests to provide access to cells beneath the crests, and still others, such as Fork U.S. Pat. No. 3,592,956 dated July 13, 1971, span two crests to provide access to cells beneath adjacent crests as well as a cell in the intervening valley. All require penetration of the decking.
In various embodiments, the preset inserts of the present invention are nestable to facilitate safe shipment to the job site, may be constructed of sheet metal, provide ready access to all three longitudinal cells, and cooperate with snap-in electrical power receptacles.
In the present invention, preset inserts may be carried solely by the cover plates, or by the decking, or by both. They may cooperate in snap-lock fashion with the grooves in the sidewall of the decking along the cover plate without significant diminution of the capacity of the cell, or may be snapped into apertures in the cover plate. In one embodiment, they may be secured directly to the cover plate and/or the cover plate and decking by threaded fasteners without penetration of such fasteners into the cells.
In yet another aspect, the present invention includes a novel lateral trench for distribution of the services to the longitudinal cells. Prior art trenches, such as disclosed in the Fork U.S. Pat. No. 3,886,702 dated June 3, 1975, generally extrude vertically adjustable side rails of aluminum. Many of the above, such as Fork, et al. U.S. Pat. No. 3,932,696 dated Jan. 13, 1976 and Penczak U.S. Pat. No. 4,056,896 dated Jan. 3, 1978, utilize the decking as the floor of the trench. Such trenches are often referred to as "bottomless". However, the use of the valley floor as the bottom of the trench requires that the concrete be interrupted by depending dams or stops in the valleys beneath the rails to prevent filling of the trench with concrete flowing upwardly from the valleys underlying the trench. The use of vertical concrete stops which depend into the intervening valleys interrupts the concrete beneath the trench and thus effects a significant loss of strength of the completed floor.
The present invention in various embodiments provides rails of sheet metal of greatly reduced cost, and snap-in bottoms for the trench intermediate the electrified cells. Such bottoms may be supported by the crests, spanning at least two of them and the included valley, and engaging the grooves in the sidewall on the outside of the decking sections. Concrete may thus flow uninterrupted through the non-electrified valley beneath the trench, significantly enhancing the strength of the composite deck.
In other embodiments, the trench bottom plates have upturned lateral edges to position the trench side rails and a pair of spaced ridges to position the power channel within the trench.
In a further aspect, the decking members, cover plates and preset inserts of the present invention may be used to electrify a formed deck supported by bar joists. Such decks are generally electrified by the suspension of a header duct between selected pairs of bar joists and by distribution ducts overlying the corrugated deck which serves as the form for the concrete slab. Ducts of this type are generally factory welded and non-nestable. More importantly the capacity of the distribution duct and the preset inserts is limited by the depth of the concrete slab. The present invention permits reversal of the position of header and distribution ducts and thus provides significantly increased capacity for the electrical services with a reduced slab thickness.
These and the many other aspects and advantages of the present invention may more readily be understood from the claims and from the following detailed description when read in conjunction with the appended drawings.